1. Field of the Invention
The present invention is generally in the field of semiconductors. More particularly, the present invention is in the field of one-time programmable semiconductor device fabrication.
2. Background Art
One-time programmable (OTP) devices are used throughout the semiconductor industry to allow for post-fabrication design changes in integrated circuits (ICs). For example, after post-fabrication functionality testing yet before sale to a customer, a semiconductor device manufacturer can program a network of OTP devices embedded in a particular semiconductor die to provide a permanent serial number encoding for that particular die. Under other circumstances, a single OTP device can be programmed to permanently enable or disable a portion of an IC at any time after fabrication, including after sale to a customer. While this functionality is in great demand, conventional OTP devices can be larger than desired, for example, making conventional OTP devices less reliable and more expensive to manufacture and integrate into semiconductor devices.
Conventional OTP devices can be fabricated using a gate structure comprising a relatively wide single channel interface with two different gate dielectric thicknesses. The thin portion of gate dielectric can be made to destructively break down and form a conductive path from gate to channel, thereby switching the conventional OTP device into a “programmed” state. This approach, however, can suffer from relatively little control over where the conductive path is formed within the thin gate dielectric, and this lack of control can result in a relatively wide distribution of impedances for programmed states. Such conventional OTP devices can, as a result, exhibit relatively poorly differentiated programmed and un-programmed states as seen by a sensing circuit, as well as programmed states having impedances that can change over the lifetime of the device. Mitigation of these issues can require additional die space for high voltage sensing circuitry and/or for redundancy techniques, for example, which can involve undesirable increases in manufacturing cost.
Thus, there is a need to overcome the drawbacks and deficiencies in the art by providing a highly reliable OTP device that can be fabricated within a smaller area than can existing conventional OTP devices.